Acute Leukemia Mouse Research Articles

AML1/RUNX1 Increases During G1 to S Cell Cycle Progression Independent of Cytokine-dependent Phosphorylation and Induces Cyclin D3 Gene Expression

AML1/RUNX1, a member of the core binding factor (CBF) family stimulates myelopoiesis and lymphopoiesis by activating lineage-specific genes. In addition, AML1 induces S phase entry in 32Dcl3 myeloid or Ba/F3 lymphoid cells via transactivation. We now found that AML1 levels are regulated during the cell cycle. 32Dcl3 and Ba/F3 cell cycle fractions were prepared using elutriation. Western blotting and a gel shift/supershift assay demonstrated that endogenous CBF DNA binding and AML1 levels were increased 2-4-fold in S and G(2)/M phase cells compared with G(1) cells. In addition, G(1) arrest induced by mimosine reduced AML1 protein levels. In contrast, AML1 RNA did not vary during cell cycle progression relative to actin RNA. Analysis of exogenous Myc-AML1 or AML1-ER demonstrated a significant reduction in G(1) phase cells, whereas levels of exogenous DNA binding domain alone were constant, lending support to the conclusion that regulation of AML1 protein stability contributes to cell cycle variation in endogenous AML1. However, cytokine-dependent AML1 phosphorylation was independent of cell cycle phase, and an AML1 mutant lacking two ERK phosphorylation sites was still cell cycle-regulated. Inhibition of AML1 activity with the CBFbeta-SMMHC or AML1-ETO oncoproteins reduced cyclin D3 RNA expression, and AML1 bound and activated the cyclin D3 promoter. Signals stimulating G(1) to S cell cycle progression or entry into the cell cycle in immature hematopoietic cells might do so in part by inducing AML1 expression, and mutations altering pathways regulating variation in AML1 stability potentially contribute to leukemic transformation.

DRUG FEVER PRODUCED BY SIX-MERCAPTOPURINE.

Case Studies1 December 1964Drug Fever Produced by Six-mercaptopurineARTHUR SAWITSKY, M.D., JAVID RUOHANI, M.D., ROBERT N. LEVY, M.D.ARTHUR SAWITSKY, M.D.Search for more papers by this author, JAVID RUOHANI, M.D.Search for more papers by this author, ROBERT N. LEVY, M.D.Search for more papers by this authorAuthor, Article, and Disclosure Informationhttps://doi.org/10.7326/0003-4819-61-6-1116 SectionsAboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinkedInRedditEmail ExcerptThe adenine analog 6-mercaptopurine is an inhibitor of growth in various microbiological systems (1), of mouse sarcoma 180 (2), and of cell growth in several types of acute leukemia in mice (3). The original report by Burchenal and his colleagues (4) that 6-mercaptopurine was effective as an antileukemic agent in human acute and chronic myeloid leukemia has been amply confirmed (5), and the drug is now an accepted agent for treatment of these diseases. Toxic reactions to the drug are frequent, the most common being excessive hematologic cellular depression, nausea, vomiting, and gastrointestinal mucosal ulceration (5). Less frequently a cholangiolitic...